Floor underlayments are used on top of subfloors such as concrete, plywood or oriented strand board prior to a finished flooring surface being placed on top of them. Such finished flooring can be typically ¾″ solid wood, engineered wood laminates, laminates or linoleum vinyl tiles. These floor underlayments typically provide a moisture barrier and may even provide a cushion along with minimizing sounds. Common materials used are recycled fibers, foam, foam beads, film or film laminates.
A new generation has prompted the popularity of condos, apartments, townhomes and multifamily homes wherein noise abatement and sound deadening have become increasingly significant. Particularly, minimizing the impact of sounds from the floors above has become a pivotal focus. Conventional floor underlayment materials have been used to reduce sound transmission including foams, plastic sheeting, compressed fibers, rubber, felts, cork, and the like. Specifically, high denier recycled fibers or foams are common floor underlayment components. Typically found between the subfloor and the finished flooring, builders often use floor underlayment to help provide a cushion or a more even walkway to the overall finished flooring. Although they may also function to dampen the noise from walking, even the current and best floor underlayments are not impactful enough in the amount of noise-level they are able to reduce.
Sound transmission, particularly in construction, is measured according to the American Society for Testing and Materials (ASTM). Noise measurements are measured in standard decibel ratings (dB-A-weighted) and are used for compliance with local, state, and/or federal requirements. There are two classes for sound ratings: Sound Transmission Class (STC) and Impact Isolation Class (IIC). STC is used to evaluate the reflected sound noise within a room (speech, music, TV, etc. . . . ) particularly through the wall structure of an apartment, house, commercial spaces, townhomes or condominiums. IIC is used to evaluate sound transmission noise of a floor/ceiling structure (walking, floor, impact, etc. . . . ) within commercial spaces, townhomes, condos, houses or apartments. Although not required, virtually all states and municipalities have set guidelines for the minimum IIC test rating that a building may have, and it's not uncommon to find minimum IIC and related STC ratings inserted into requests for proposals from architects and other designers. The International Code Council states the minimum acceptable level of performance for both STC and IIC is 50-IIC. The “preferred” level of performance for STC and IIC is 60.
Of particular interest to IIC ratings, one common misconception is that using an increased thickness of an underlayment will result in a better IIC rating. While this is generally true, this is not economically viable. The initial doubling of a material may increase performance but may still fail to meet an acceptable IIC rating and/or create commercial value. Thus, the addition of layers can cause a diminishing return. For example, suppose a 2 mm underlayment improves an assembly's IIC rating by 12 points. Doubling it to 4 mm may give another 3-5 points of improvement. Increasing the thickness beyond that point may add another 1-2 points for a few more millimeters; however, the amount of improvement begins to plateau with the increased thickness. Creating thick underlayments based solely on layering, therefore, is not a reasonable solution for resolving noise issues.
Many current floor underlayments include additional backing adhered to the underlayment to provide protection against spills, such as liquids. While offering a protective solution to the floors, such a system creates an unbreathable barrier. Moreover, moisture can get trapped within the flooring system leading to mold, mildew and other disadvantages.
Several floor underlayment systems can be found in the industry to tackle the foregoing problems including, but not limited to, a poured underlayment system such as LEVELROCK® floor underlayment sold by United States Gypsum Company of Chicago, Ill. (USG). LEVELROCK® underlayment is a mixture of Plaster of Paris, Portland cement and crystalline silica. Another system includes US 2010/0077684 to Socha, filed Sep. 22, 2009, which, provides an underlayment acoustical mat that is placed upon a subfloor with a poured underlayment (such as LEVELROCK®) being combined at the jobsite for application on to the mat. The finished flooring is then installed over the set underlayment and mat. Although such a system may address noise concerns, it must be installed during construction which may eliminate its use in pre-existing buildings or homes and may be entirely cost prohibitive for most residential home constructions or residential renovations.
Thus, it is desirable to provide a floor underlayment that can be installed between a subfloor and finished flooring without the need for a poured underlayment cement system. Additionally, it is desirable that such a floor underlayment not only significantly reduces sound impact, but is breathable and provides for a barrier against liquids.